If you watch elite runners before a hard workout or race, you'll often see what looks like a workout in itself. In addition to jogging, you'll see lots of drills, skipping, sprinting and other vigorous activities as part of their warm-up. The shorter the race, the truer this is. A new study adds to not only elite best practices but also prior research in support of including high-intensity work soon before you want to run fast.

In the new study, published in the Journal of Science and Medicine in Sport, 11 well-trained distance runners went through a warm-up and race simulation on two occasions. Before both, they did 10 minutes of easy jogging, 5 minutes at a brisk but not all-out pace, and six 10-second striders, or accelerations at mile race pace or faster. After a 10-minute rest, the runners then did a series of jumps, another submaximal 5-minute run, and then a treadmill test of peak running speed. The only difference between the two occasions was that during one the runners wore a weighted vest while doing their 10-second striders.

The effect of the vest on the subsequent tests was significant. The participants' running economy was 6% better on the post-striders 5-minute run, and their peak running speed 2.9% faster, when they had worn the vest as part of their warm-up. Running economy is essentially a measure of efficiency; better running economy should mean that you can run faster at the same effort level, or that a given pace will feel easier.

The researchers think that the increased leg stiffness noted in the post-striders jumps when the runners wore the vest accounts for these changes. Although leg stiffness sounds like something runners would want to avoid, research has consistently shown that, in the type measured in this study, it leads to better running economy, at least for short, fast races. This is why most racing flats are firmer than most training shoes.

While you're probably not going to order a weighted vest as soon as you finish reading this article, this study is worth keeping in mind as an example of how counterintuitive good warm-up practices might seem. At a less dramatic level, you've probably noticed a similar phenomenon during hard workouts, when you feel much better on the second or third repeat than the first. Experiment with your warm-ups before hard workouts and low-key races to see whether a bit more work before leads to greater satisfaction after.